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Preparation and magnetic properties of CoFe_2O_4/TiO_2 composite films

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Chinese Science Bulletin 2008年第12期53卷 1817-1823页

作者： TIAN XiaoXia qu shaobo PEI ZhiBin WANG BinKe College of Science Air Force Engineering University Xi'an 710051 China Electronic Materials Research Laboratory and Key Laboratory of Ministry of Education Xi'an Jiaotong University Xi'an 710049 China

Using (Ti(OC_4H_9)_4) and metal chlorates as starting materials, CoFe_2O_4/TiO_2 composite films were pre-pared by sol-gel method. The effects of heat treatment temperature and pH of the precursor on micro-structure and magnetic properties were studied. The phase structure of the samples was examined by X-ray diffraction. The microstructure was examined by scanning electron microscope, atomic force microscope and polarized microscope. The magnetic property was measured by vibrating sample magnetometer. The results show that the crystals of different phases grow up independently. CoFe_2O_4 is uniformly embedded into the TiO_2 matrix in the prepared composite films, and the growth of com-posite films is dependent on the heat treatment temperatures and PH of the precursor. The average size of CoFe_2O_4 crystal is 19 nm in Nanocomposite film prepared when the heat treatment temperature is 800℃ and the pH of the precursor is between 2 and 3. The magnetism of the composite films is en-hanced as the heat treatment temperature increases.

关键词：磁性薄膜二氧化钛物理性质

Microstructure and properties of Ga-modified 0.7BiFeO_3-0.3BaTiO_3 solid solution

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Chinese Science Bulletin 2007年第20期52卷 2747-2752页

作者： LIU XiaoHui XU Zhuo qu shaobo WEI XiaoYong CHEN JiangLi Electronic Materials Research Laboratory Key Laboratory of Ministry of Education Xi'an Jiaotong University Xi'an 710049 China

Binary solid solutions 0.7Bi (GaxFe1-x)O3-0.3BaTiO3 (x = 0, 0.025, 0.05, 0.1) ceramics were prepared by traditional ceramic process. All the ceramic samples showed single perovskite phase except the sam- ple with x = 0.1. The effects of gallium doping on microstructure, ferromagnetic, ferroelectric, dielectric properties and conductivity were investigated. The results indicated that Ga-dopant could improve the sintering ability of the solid solution when the Ga content x was below 0.05. When x was over 0.05, the sintering ability of the solid solution was weakened, and the phase structure of 0.7BiFeO3-0.3BaTiO3 solid solution changed from rhombohedral phase into tetragonal ferroelectric phase. The electrical resistivity increased with the Ga content increasing. Both ferroelectricity and ferromagnetism were observed in all the ceramic samples. With the Ga content increasing, the remanent magnetization Mr increased and the magnetic coercive field Hc decreased. However, the remanent polarization Pr fluctu- ated, increasing firstly and decreasing later.

关键词：电阻率铁电性铁磁性镓改性

Improvement in the piezoelectric temperature stability of(K_(0.5)Na_(0.5))NbO_3 ceramics

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Chinese Science Bulletin 2011年第22期56卷 2389-2393页

作者： ZHAO JingBo DU HongLiang qu shaobo ZHANG HongMei XU Zhuo The College of Science Air Force Engineering University Xi'an 710051 China State Key Laboratory of Electrical Insulation and Power Equipment Xi'an Jiaotong University Xi'an 710049 China Electronic Materials Research Laboratory Key Laboratory of Educational Ministry Xi'an Jiaotong University Xi'an 710049 China

Through an analysis of the temperature stability of(K0.5Na0.5)NbO3(KNN)based ceramics and KNN solid solutions,we propose a method to enhance the temperature stability of KNN *** materials are valuable for their piezoelectric *** verify the feasibility of this method,0.9(K1-xNax)NbO3-0.06LiNbO3-0.04CaTiO3(KNLN-CaTiO3)ceramics were designed,and their structure and properties were *** results show that KNLN-CaTiO3(x=0.54)ceramics have a good temperature stability over a wide temperature range(25-320°C).Also,they have good piezoelectric properties(d33=152 pC/N in x=0.54).This result confirms the feasibility of our proposed solution for improving the piezoelectric properties of KNN-based ceramics that have poor temperature stability.

关键词：温度稳定性压电性能陶瓷设计 CaTiO3 KNN 温度范围材料

Tailoring circular dichroism via the Born-Kuhn model for meta-holograms

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Science China(Physics,Mechanics & Astronomy) 2022年第10期65卷 83-92页

作者： He Wang Hongqiang Zhou Tianhao Li Zhe Qin Chenchen Li Xin Li Yongfeng Li Jieqiu Zhang shaobo qu Lingling Huang Department of Basic Sciences Air Force Engineering UniversityXi’an 710051China Beijing Engineering Research Center of Mixed Reality and Advanced Display School of Optics and PhotonicsBeijing Institute of TechnologyBeijing 100081China Department of Physics and Optoelectronics Faculty of ScienceBeijing University of TechnologyBeijing 100124China

Chirality, as one of the ubiquitous properties in nature, has aroused striking attention in the fields of physics and materials sciences. For tailoring of light with more degree of freedom, circular dichroism has been considered as the auxiliary dimension to improving such an issue. Inspired by the Born-Kuhn plasmonic oscillation model, we demonstrate and discuss a chiral resonator to reveal reverse circular dichroism within two separate frequency bands in the microwave regime. The underlying physical mechanisms of bonding and anti-bounding modes are analyzed via transmission/reflection spectra and surface current distributions for different chiral enantiomers. To leverage the proposed paradigm to the application levels, especially for metaholography, we conduct the numerical simulation and experimental demonstration of two proofs of principles. Based on the Pancharatnam-Berry phase/amplitude modulation and complex-amplitude manipulation, respectively, the meta-holograms with independent targets of reconstructing images in full-space and reflected regions are achieved. Significantly, our paradigm may promise further applications in spin-controlled meta-devices for image processing, information encryption, anti-counterfeiting,remote sensing, and radar systems.

关键词： circular dichroism Born-Kuhn model meta-hologram electromagnetic manipulation

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Polarization insensitive metamaterial absorber based on E-shaped all-dielectric structure

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Journal of Advanced Dielectrics 2015年第1期5卷 65-70页

作者： Liyang Li Jun Wang Hua Ma Jiafu Wang Hongliang Du shaobo qu College of Science Air Force Engineering UniversityXi'an 710051 ShaanxiP.R.China

In this paper,we designed a metamaterial absorber performed in microwave frequency *** absorber is composed of E-shaped dielectrics which are arranged along different *** E-shaped all-dielectric structure is made of microwave ceramics with high permittivity and low *** about 1 GHz frequency band,more than 86%absorption efficiency was observed for this metamaterial *** absorber is polarization insensitive and is stable for incident *** is figured out that the polarization insensitive absorption is caused by the nearly located varied resonant modes which are excited by the E-shaped all-dielectric resonators with the same size but in the different *** E-shaped dielectric absorber contains intensive resonant *** research work paves a way for designing all-dielectric absorber.

关键词： Absorber all-dielectrics E-shaped microwave ceramics

Optical transparent infrared high absorption metamaterial absorbers

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Journal of Advanced Dielectrics 2018年第1期8卷 56-63页

作者： Jingfan Yang Cuilian Xu shaobo qu Hua Ma Jiafu Wang Yongqiang Pang College of Science Air Force Engineering University Xi’an 710051P.R.China

In this work,an optical transparent infrared high absorption metamaterial absorber is proposed based on indium tin oxide(ITO)*** to the fact that ITO holds high reflectivity property in infrared region while transparent in optical region,ITO can be used in the application of Surface Plasmon *** this design,three kinds of infrared metamaterial absorbers were *** of them can achieve high absorption at 10.6μm while remaining transparent in visible *** equivalent circuit model was served as design *** infrared absorption efficiency was numerically calculated and the mechanism analysis is given in the *** simulation results show that all three structures can achieve high absorption efficiency at 10.6μm under TE/TM *** absorption remains high when the incident angle is less than 70°.Experimental results exhibit good accordance with simulation.

关键词： ITO infrared metamaterial absorber visible transparent insensitive absorption

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小型化频率选择表面研究现状及其应用进展

材料导报 2019年第5期33卷 881-893页

作者：王晖屈绍波空军工程大学研究生院西安710051

频率选择表面是一种在平面内排布的二维周期阵列,由金属贴片单元或孔径单元构成,其对不同频率电磁波呈现不同的滤波响应,被广泛应用于雷达隐身、卫星通讯和电磁兼容等领域。随着应用对技术的要求不断提高,传统频率选择表面难以满足实际... 详细信息

频率选择表面是一种在平面内排布的二维周期阵列,由金属贴片单元或孔径单元构成,其对不同频率电磁波呈现不同的滤波响应,被广泛应用于雷达隐身、卫星通讯和电磁兼容等领域。随着应用对技术的要求不断提高,传统频率选择表面难以满足实际应用。原因有:(1)传统频率选择表面较大的单元尺寸会导致单元谐振时栅瓣过早出现,对传输特性产生不良影响;(2)传统频率选择表面较大的单元尺寸导致其很难在有限空间的区域内以及不规则天线罩上使用,且大尺寸使得现有工艺很难完成贴装布阵。而单元尺寸远小于工作波长的小型化频率选择表面MEFSS的出现为解决上述问题提供了新的思路,其优势日益凸显了自身的价值,逐渐发展成为新的研究方向。最初的小型化频率选择表面通过结构上的交叉、旋绕、连接等模式来达到缩小单元尺寸的目的,最典型的方法就是单元的卷曲、交指设计。为了突破"单元尺寸与谐振波长一致"这一限制,实现小尺寸结构可以控制长波长谐振,通过金属贴片和网格经介质级联,产生了基于容性表面与感性表面耦合技术的小型化频率选择表面。该频率选择表面通过减小单元的有效电尺寸来实现小型化。耦合型双屏小型化频率选择表面主要分为:网栅及其互补结构、网栅和方环贴片阵列结构、方环贴片及其互补结构。这三种典型的耦合双屏结构是研究复杂耦合型小型化频率选择表面结构的基础。由于前两类频率选择表面在实现小型化特性时都无法摆脱周期单元尺寸的制约,若需要更高的小型化需求时则难以实现。而加载无源集总元件(电容器、电感器)的频率选择表面可以增大等效电感L以及等效电容C的值,能够更大程度地缩小单元的有效电尺寸,使得频率选择表面小型化程度更高。为了拓展小型化频率选择表面的功能,在普通小型化频率选择表面单元或介质衬底上加入有源器件(变容二极管和PIN二极管等)或采用特征媒质作为介质衬底等组成有源小型化频率选择表面。该频率选择表面在实现小型化特性的同时,通过对有源器件的调节来控制该频率选择表面的通带开关和变频特性等。本文从单元卷曲和交指设计、基于容性表面与感性表面耦合技术设计、加载无源/有源集总元件技术设计等方面综述了小型化频率选择表面的研究状况。随后,对小型化频率选择表面在实际中的应用进行了介绍并对其未来发展方向进行了展望。

关键词：频率选择表面空间滤波器小型化电磁兼容天线罩

quadruple-band metamaterial absorber based on the cuboid dielectric particles

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Journal of Advanced Dielectrics 2018年第4期8卷 6-13页

作者： Wenjie Wang Mingde Feng Jun Wang Zhiqiang Li Jiafu Wang Hua Ma shaobo qu Department of Basic Sciences Air Force Engineering University Xi’an 710051ShaanxiP.R.China

In this work,a quadruple-band dielectric metamaterial absorber(MMA)was proposed and studied,which is composed of eight cuboid dielectric particles and a metallic ground *** electromagnetic wave is incident on the dielectric particles,dielectric particles act as resonators and produce abundant resonant modes,which can result in perfect *** simulation,four absorption peaks are observed at 9.13,9.62,10.0 and 10.46 GHz with 88%,89%,100%and 96%,*** adjusting geometry parameters of the dielectric particles,dielectric MMAs with different bands can be *** investigation shows that the absorption peaks can be changed by increasing the permittivity of the *** on the designing technique of using simple cuboid dielectric particles directly acting as resonator,this work provides a simple method to construct multiband alldielectric MMA.

关键词： Cuboid dielectric particles metamaterial absorbers quadruple-band electric field magnetic field.

A transmit/reflect switchable frequency selective surface based on all dielectric metamaterials

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Journal of Advanced Dielectrics 2015年第4期5卷 61-66页

作者： Fei Yu Jun Wang Jiafu Wang Hua Ma Hongliang Du Xu Zhuo shaobo qu Department of Mathematics and Physics College of Science Air Force Engineering University Xi'an 710051P.R.China Electronic Materials Research Laboratory Xi'an Jiaotong University Xi'an 710049P.R.China

In this paper,we propose a novel transmit/reflect switchable frequency selective surface(FSS)in millimeter wave band based on the effective medium theory under quasi-static limit,which is designed with square-hole elements cut from continuum dielectric *** building elements of the surface are composed of all dielectric metamaterial rather than metal *** proper structural design and parameters tuning,the resonance frequencies can be tuned *** frequency response of the surface can be switched from that of a reflecting structure to a transmitting one by rotating the surface 90°,which means under different incident *** reflective response can be realized due to the effect of electric and magnetic *** analysis shows that the reflective response arises from impedance mismatching by electric and magnetic *** the transmitting response is the left-handed passband,arises from the coupling of the electric and magnetic *** addition,effective electromagnetic parameters and the dynamic induced field distributions are analyzed to explain the mechanism of the *** method can also be used to design switchable all-dielectric FSS with continuum structures in other frequencies.

关键词： Switchable FSS dielectric resonance